Kidney Ultrasound Scan: What Is It, How It Works And Why Do You Need It

What is a kidney ultrasound?

A kidney ultrasound, also known as a renal ultrasound test, is a non-invasive diagnostic ultrasound procedure that uses high-frequency sound waves to create detailed images of your kidneys, bladder and uterus. This non-invasive procedure allows healthcare professionals to assess the size, shape, and location of the kidneys, as well as detect any potential issues such as cysts, tumours, or obstructions.

How do the kidneys work?

The kidneys are vital organs responsible for filtering and removing waste products like urea from the blood and maintaining potassium, sodium, and water balance in the body. They also produce erythropoietin, a hormone that regulates blood pressure, stimulates red blood cell production, and activates vitamin D for bone and muscle health.

When would I need to get a kidney ultrasound?

Your healthcare provider may recommend a kidney ultrasound if they require more information about causes for kidney issues or for other various reasons, including:

1) Diagnosis of medical conditions

Kidney ultrasound is often recommended when your doctor suspects kidney stones, cysts or tumours. If you're experiencing severe flank pain (back and sides of your abdomen, between your hips and lower ribs), blood in urine (haematuria), or unexplained abdominal discomfort, an ultrasound can help us visualise these conditions. This non-invasive imaging technique uses sound waves to create detailed images of your kidneys, allowing doctors to identify stones as small as a few millimetres.

For suspected tumours or cysts, ultrasound serves as an initial diagnostic tool to determine their size, location and characteristics. It helps distinguish between solid masses and fluid-filled cysts, which guides further management decisions. Your doctor may recommend additional imaging tests such as CT scans or MRIs depending on the ultrasound findings.

2) Kidney infection or damage

When you present with symptoms of kidney infection (pyelonephritis) such as high fever, flank pain, frequent urination or burning sensation during urination, a kidney ultrasound can reveal enlargement of the kidney, areas of inflammation, or abscesses that indicate infection.

The scan can also evaluate kidney damage from trauma, providing immediate information about potential bleeding around the kidney (perinephric haematoma), structural damage, or disruption to blood flow, which is crucial for determining whether conservative management is sufficient or if urgent intervention is required.

3) Chronic kidney disease

For patients with chronic kidney disease (CKD), kidney ultrasound offers valuable information about kidney size, structure and progression of the condition. Kidneys affected by long-term damage often appear smaller and more echogenic (brighter on ultrasound) than healthy kidneys.

Ultrasound also helps assess complications such as hydronephrosis (swelling of the kidney due to urine backup) or the development of kidney cysts in conditions like polycystic kidney disease, allowing your healthcare team to monitor changes over time and adjust treatment plans accordingly.

4) Assessment of bladder function or urinary conditions

Kidney ultrasound often includes examination of the bladder and urinary tract, making it useful for diagnosing conditions such as urinary tract infections, urinary retention, or vesicoureteral reflux (when urine flows backward from the bladder to the kidneys).

For patients with suspected urinary obstruction, the scan can identify blockages in the urinary tract and measure residual urine volume in the bladder after voiding, which helps evaluate bladder emptying efficiency and manage conditions that affect both the kidneys and the lower urinary tract.

5) Kidney biopsies or fluid drainage procedures

When doctors need to collect a tissue sample from your kidney through a biopsy or perform drainage procedures such as nephrostomy (draining urine from an obstructed kidney) or abscess drainage, ultrasound guidance ensures accurate needle or catheter placement.

The real-time imaging allows the doctor to visualise the kidney throughout the procedure, avoiding important structures like blood vessels and determining the optimal entry point and path for instruments, which significantly improves safety and effectiveness while reducing potential complications.

6) Monitoring kidney conditions

Regular ultrasound monitoring is crucial for patients with known kidney conditions such as polycystic kidney disease, recurrent kidney stones, or a history of kidney cancer, as well as for kidney transplant recipients.

For existing conditions, follow-up scans help track changes in abnormalities and detect new developments early, while for transplant patients, ultrasound evaluates blood flow to the new kidney, checks for potential complications like fluid collections or obstruction, and monitors for signs of rejection, ensuring the transplanted kidney is functioning properly.

If you have any of the concerns mentioned above and want to get a kidney ultrasound, please request an ultrasound appointment at Thomson Medical.

How does a kidney ultrasound work?

During this medical procedure, a trained ultrasound technician will apply a special ultrasound gel to your skin to act as a lubricant and use a handheld device called a transducer.

The ultrasound transducer emits high-frequency sound waves that penetrate your body and bounce off internal organs and tissues. These sound waves create echoes that are then converted into real-time ultrasound images on a computer screen, allowing the ultrasound technician to examine your kidneys and related structures to check for any potential health conditions.

How can I prepare for my kidney ultrasound?

Preparation for a kidney ultrasound is typically minimal, and in most cases, you do not need to prepare for a kidney ultrasound. However, your healthcare provider may instruct you to:

• Drink plenty of water, about 1 litre, one hour before the exam to ensure a full bladder, which can improve ultrasound image quality to evaluate your bladder function and capacity.

• Wear comfortable, loose-fitting clothing.

• In some situations, your doctor may request you to avoid eating for a few hours before the procedure.

What happens during the kidney ultrasound?

The ultrasound examination usually takes around 20 to 30 minutes. During a kidney ultrasound, the process is usually as follows:

1. You will be required to remove your clothing and jewellery and change into a hospital gown.

2. Afterwards, you will need to lie down on an exam table located next to the ultrasound equipment.

3. An ultrasound technician will apply the ultrasound gel onto your skin where they plan to place the transducer. It may feel slightly cold at first.

4. A radiologist places the transducer on your skin around your abdomen. They'll gently press down and move it around very slowly with one hand. With the other hand, they'll control the ultrasound machine and take the images.

5. During the test, you might need to hold your breath several times or roll onto your side. Your ultrasound technician may also ask you to go to the bathroom during the test so they can get images of your bladder when it's empty.

6. A radiologist will then review your ultrasound images and discuss their findings with your healthcare provider.

What can I expect after the kidney ultrasound?

After the ultrasound, you can immediately resume your normal activities. The results are usually available within 24 to 48 hours after the test; however, this time may differ depending on your healthcare provider. Your doctor will then contact you to discuss the results and any necessary follow-up steps.

How do I interpret the results of my kidney ultrasound?

Your healthcare provider will interpret the results of your kidney ultrasound and explain them to you. The ultrasound results can include:as 

• Visual images to provide a clear image of your internal structure, such as, kidney size, shape, and position.

• Detection of abnormalities such as the presence of kidney stones, cysts, tumours, or infections.

• Blood flow evaluation to assess blood flow within your kidneys by analysing the movement of blood vessels in the images to identify circulation issues or blockages.

• Functional assessments to offer insights into your kidney functions, such as searching for indications of chronic kidney disease.

However, the results will be unique to your situation and depend on why you had the ultrasound. There may also be a small chance that your healthcare provider will order additional imaging tests, such as kidney function tests or a kidney biopsy. Based on the findings, your doctor will determine if any treatment plans are needed.

Renal ultrasound scan

Kidney ultrasound scans are a safe, painless, and valuable type of ultrasound that help healthcare providers assess your kidney health and function. They play a crucial role in detecting various kidney conditions and guiding potential treatment plans. If you have concerns about your kidney health, please consult your doctor to determine if you require a kidney ultrasound.

For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.

FAQ

Does getting a kidney ultrasound pose any risk?

No, kidney ultrasounds are considered very safe, as they use sound waves rather than radiation.

Can you detect a tumour in a kidney via ultrasound?

Yes, kidney ultrasounds can detect tumours and other masses in the kidneys.

Can an ultrasound show if your kidneys are failing?

While ultrasound can show changes in kidney size and structure that may indicate kidney disease, additional tests are typically needed to confirm kidney failure.

What are the three early warning signs of kidney failure?

Early signs of kidney failure may include changes in urination, swelling in the legs, ankles, or feet, and fatigue. However, these symptoms can be associated with other conditions as well.

Can children get kidney ultrasounds?

Yes, kidney ultrasounds are safe and commonly performed on children to evaluate various kidney and urinary tract conditions.

What can a kidney ultrasound diagnose?

Kidney ultrasounds can help diagnose kidney stones, cysts, tumours, obstructions, infections, and structural abnormalities of the kidneys and urinary tract.

What are the benefits of getting a kidney ultrasound?

Kidney ultrasounds are non-invasive, painless, and do not use radiation. They provide real-time images of the kidneys and can help diagnose various conditions quickly and safely.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.